The Colorado Department of Transportation (CDOT) joined TPF-5(213) as a state partner in 2010. CDOT participated on the advisory board for the Roofs to Roads Colorado Project that started in 2009, to promote the market development of RAS in Colorado. In April 2010, Boulder County, in partnership with Roofs to Roads Colorado, completed a demonstration project placing post-manufactured RAS at 5% of the total mix in an overlay project on North 63rd Street. Additional projects using post-consumer RAS were completed in 2010 by Colorado county agencies.
In the fall of 2010, CDOT organized a Recycled Asphalt Shingle (RAS) Task Force to develop a draft specification for the use of RAS in asphalt applications. The task force was created in partnership with the Colorado Asphalt Pavement Association. Participating members included shingle recyclers, roofing contractors, asphalt producers and agency officials. Three meetings were held, the last meeting was at the end of March 2011, and a RAS Standard Special Provision Provision to modify CDOT's Standard Specifications for Road and Bridge Construction was released. RAS is allowed in hot mix asphalt up to a maximum of 5.0 percent for all lifts; the deleterious content is limited to 1.5 percent by mass as determined by material retained on the #4 sieve; and the moisture contents cannot exceed 15% by mass. CDOT is committed to achieving quality control protocols to ensure that asphalt mixes using RAS are equal or better than the asphalt mixes used in pavements today. CDOT goals for the study are to look at the performance of RAS and RAP in HMA applications and develop a specification to address quality control and quality assurance when utilizing RAS.
On April 26, 2011, CDOT in partnership with Iowa State University (ISU) hosted the, 'Colorado Reclaimed Asphalt Shingle Workshop'. The workshop brought partners together to discuss roles and responsibilities of each of the shingle recycling partners to achieving a quality end RAS product.
CDOT Region 4 identified a demonstration project on U.S. 36 between Denver and Boulder. The project included one test section and a control section and was completed in June/July 2011. The test section included 15% fine recycled asphalt pavement (RAP) and 3% post-manufactured recycled asphalt shingles (RAS). The control section included 20% fine RAP.
Colorado DOT Partner:
Roberto E. DeDios, P.E.
Pavements and Materials Research Engineer